Press the room number to unlock the doorbell, but you can't talk.

If the above faults occur, the principle analysis shows that the bell signal line from the intercom to your home is good. If you can't speak, you can ask the neighbors if they are normal first. If it is normal, you need to check your own line, especially the switch (the switch pressed by the receiver) in the indoor hang-up often has poor contact failure, which will hinder the transmission of voice and unlocking signals. If the neighbor's house is not normal, check the public circuit first. The common fault is that each floor has a junction box, which is used to distribute to all users on each floor. During construction, most of the wiring will be messed up, and the contact resistance will become larger after a long time, and the above faults will also occur.

(Note: The above overhaul ideas are aimed at the direct pressure intercom doors of 2-wire and 4-wire that are common in the market at present)